Background The West Indian manatee (Trichetus manatus manatus) is an endangered species (IUCN red list, endangered status), which has disappeared from Guadeloupe. This large herbivorous marine mammal is, however, an emblematic symbol of Guadeloupean biodiversity and is part of the Creole culture. Extinct from the Lesser West Indies due to overhunting in the colonial era, the West Indian manatee population is now also threatened in the rest of the Caribbean. Scarce are the countries where more than 100 manatees remain. French Guyana being the only European-administered territory possessing a manatee population. Objectives The main objective of the LIFE SIRENIA project is to re-establish a population of West Indian manatee in Guadeloupe. The project aims to reintroduce and monitor 10 manatees; support operational and scientific exchange and conservation initiatives; and educate and involve the public in manatee conservation and environment protection activities. This project will be the first such marine mammal reintroduction, and thus will be an important demonstration of marine mammal conservation for organisations in similar Caribbean regions (e.g. St Maarten, Martinique) where the results could be reproduced. Expected results: Ten West Indian manatees introduced and monitored in the natural environment of the Grand Cul-de-Sac Marin Bay, with normal wild behavior developing; Target users (100 fishermen, 10 tour operators, and 100 boatmen) informed and involved in the protection of the manatee and its natural environment; At least 20 schools made aware of the protection of the manatee and its natural marine environment in Guadeloupe; Data, experience and knowledge of the project shared and discussed with scientists and public actors in France, the Caribbean and through specialised networks (e.g. LIFE); and Numerous publications, including guidelines on best practices for marine mammal reintroductions, incorporating a set of protocols for animal management and reintroduction; films (educational and for the general public) presenting the project and its implications; scientific studies of the natural environment in Guadeloupe; and a website devoted to the project.